Crouzon syndrome is an autosomal dominant genetic disorder known as a branchial arch syndrome. Specifically, this syndrome affects the first branchial (or pharyngeal) arch, which is the precursor of the maxilla and mandible. Since the branchial arches are important developmental features in a growing embryo, disturbances in their development create lasting and widespread effects. This syndrome is named after Octave Crouzon, a French physician who first described this disorder. He noted the affected patients were a mother and her daughter, implying a genetic basis. First called “craniofacial dysostosis”, the disorder was characterized by a number of clinical features. This syndrome is caused by a mutation in the fibroblast growth factor receptor II, located on chromosome . Breaking down the name, “craniofacial” refers to the skull and face, and “dysostosis” refers to malformation of bone.Now known as Crouzon syndrome, the disease can be described by the rudimentary meanings of its former name. What occurs in the disease is that an infant’s skull and facial bones, while in development, fuse early or are unable to expand. Thus, normal bone growth cannot occur. Fusion of different sutures leads to different patterns of growth of the skull. Examples include: trigonocephaly (fusion of the metopic suture), brachycephaly (fusion of the coronal suture), dolichocephaly (fusion of the sagittal suture), plagiocephaly (unilateral premature closure of lambdoid and coronal sutures), oxycephaly (fusion of coronal and lambdoidal sutures), Kleeblattschaedel (premature closure of all sutures).
Crouzon described an affected family pedigree in 1912. He listed four major charecteristics of the disease: exorbitism , retromaxillism , inframaxillism, and paradoxic retrogenia . Premature fusion of sutures may occur at the level of the cranial vault ; bilateral coronal prematüre fusion is the most common and results in a brachycephalic appearance. Other forms of premature suture synostosis (i.e. saggital, lambdoid , or metopic ) may also occur in Crouzon syndrome. In additional to cranial vault synostosis , there is a variable degree of symmetric hypoplasia or dysplasia of the orbits, zygomas , and maxilla . The mandible has normal growth but may become secondarily deformed with an obtuse ramus / inferior border angle and a vertically long chin . In general the soft tissue envelope is normal except for a variable degree of upper eye lid ptosis and inferiorly positioned lateral canthi . In patients with classical findings , the cranial vault is either brachycephalic or oxycephalic the orbits are shallow with proptotic eyes, and the midface is flat with an Angle class lll malocclusion . Nasal airflow is dimnished with partial obstruction , and a mouth breathing is common.